Stamp-mill.



No. 634,4. Patented Oct. 3, I899.

A. c. PRATT & c. A. LA GRAVE. STAMP MILL.

(Application filed May 14, 1898. (No Model.) 2 Sheets8heet l,

Q INVENTORS law 3 W A/lvrney N0. 634,40. Patented Oct. 3, I899.

A. C. PRATT & C. A. LA GRAVE. STAMP MILL.

7 (Application filed. May 14, 1898.) (N 0 ll 0 d e l 2 Sheets-Sheet 2 WITNESSES l/VVENTOR A [turkey UNIT D STATES PATE T Priest ALEXANDER O. PRATT AND CHARLES A. LA GRAVE, OF CARSON, NEVADA, ASSIGNORS TO THE IDEAL STAMP MILL COMPANY, OF NEVADA.

STAMP-MILL.

SPECIFICATION forming part Of Letters Patent NO. 634,417, dated October 3, 1899.

Application filed May 14,1898. Serial No- 680.684. (No model.)

The object of the invention is to produce a stamp-mill in which the momentum of the moving parts shall be largely utilized to ac- I complish the desired work and in which the blow of the stamp shall be given at high velocity and without retardation from the slowing down of a prime mover, as of a piston nearing the end of its stroke or a crank apzo proaching its dead-center.

This stamp-mill contains many improvements in details of construction and adaptation of parts in addition to the generic improvements above mentioned.

Figure 1 is a representation, partly in elevation and partly in section, of a stamp-mill embodying the main features of the invention. Fig. 2 is a partial detail plan of the stamp-mill. Fig. 3 is a perspective view of mortar-screen.

the mortar, screen, and easing. broken perspective view of the mortar-body. Fig. 6 is a broken perspective of mortar and easing. Fig. 7 is a plan of the mortar-body.

, The numeral 1 indicates a cylinder of a steam or other engine of usual construction having valves and reversing-gear and connected by a piston-rod 2 to the driving mechanism of the stamp-mill. The piston-rod may 0 be supported in a lubricating-box 3. Any suitable valves and gear may be employed to control the movement of the engine, and the reciprocating movement of rod 2 may be obtained otherwise than directly from the piston of a cylinder, although we consider such direct application more economical. The p itman-bar ewe prefer to make of wood, (for lightness and convenience,) with metallic Fig. 4 is a vertical section of Fig. 5 is a straps 5 connected thereto by bolts 6 and to the piston-rod 2 by a pin .7, passing. through the straps and rod. By havinga number of bolt-holes for bolts (5 or by means of other suitable and usual mechanism the length of pitman 4; may be adjusted. The end of pitman or connecting bar 4 remote from the cyl- 5 5 inder we connect to the operating-arm'lO of the stamp, but in such manner as to permit a certain freedom of movement to said arm independently of the reciprocation of the pitman or connecting bar. For this purpose we connect a loop or clevis 8 to the bar 4, said loop .or clevis being connected to the bar, as by bolts 9, and having an elongated opening between the end of the bar and the outer end or loop of the strap or clevis. Arm 10 is rigid with shaft 11, which shaft is journaled in suitable bearings 12, so as to rock therein. The whole machine may be supported on any suitable foundation, as indicated at A. The loop 8, being considerably longer than the width of arm 10, preferably has elastic packing 13, secured in the loop at each end, but still leaving room for play or lost motion, and a set-screw 14 at the end of the loop may be used to limit the amount of play arm 10 may have between the buffers 13. Shaft 11 carries the oscillating stamp,'which we will now describe. The segment 20 is a heavy casting, having stamp-shoes 21 at each end and connected by two or more arms22 to the hub 23 on shaft 11. Segment 20 is preferably curved on the arc of a circle or ellipse. Stampdies 30 under the shoes at the endsof segment 20 form the supports for the rock, ore, or other material to be crushed in mortars 50, one mortar for each stamp. As the segment 20 is preferably a metallic casting, it is of course rigid, as are the arms 22, and all will move together with shaft 11.

Now assuming the parts to be in position of Fig. 1 the movement of bar 4 toward the left will bring the buffer 13 at the right of arm 10 against said arm and rock the arm, shaft, and segment toward the left. The impelling force of the motor will be imparted to 5 the segment 20, and as the parts are very nearly balanced there is not much loss of power by overcoming the weight of parts. The friction of the shaft- 11 in the bearings 12 is but slight, and these bearings 12 are somewhatremote from the stamping-heads and not liable to be obstructed by grit and dust from the stamps. The momentum of the piston-rod or other motor being communicated to the stamp, the momentum of the moving parts carries the stamp forward at a high speed, although the piston or other motor may lose much of its velocity near the close of its stroke, the space for lost movement of arm 10 in loop 8 permitting this free movement until shoe 21 strikes the object to be crushed on die 30 at the left. The reverse movement of bare quickly brings the other buffer 13 against arm 10, and the stamp is swung in opposite direction with the same freedom of movement to convert momentum into striking force without check due to the slowing of the prime mover near the end of its stroke or reciprocation and without shock of the blow to such prime mover. By the application of this principle of nearly balancing the stamp and striking blows alternately at opposite ends of the stamp and permitting a freedom of movement to the stamp, as indicated, we are enabled to deliver crushing blows with greater rapidity and effectiveness and with less strain and shock to the driving-motor than with any other stamp-mill with which we are acquainted.

The intent of our apparatus is to depend as little as possible on gravitation, as manifested by the downward movement of astamp or weight, and as much as possible on the quick transformation of momentum into striking force without retardation. The stamp being balanced so that it can be moved quickly in either direction and each stampshoe having a separate mortar, there is no wasted time or energy, as in lifting a stamp and causing it to strike a blow only on its downward movement. As the striking force of a stamp or other moving object is the square of its velocity multiplied by the weight, it is highly important that the velocity of the stamp shall not be diminished prior to the delivery of its blow on the ore to be crushed, and this great advantage we utilize very fully in the construction described. It is further of advantage to utilize the movement of the stamp in both directions, as we have done. 13y carefully graduating the feed of material to the stamps the eifective force of the blows of the stamps may be absorbed by the work performed in crushing the material, and every reversalof movement of the driver finds the stamp at rest, nearly balanced, and ready for movement in reverse direction.

This stamp must be distinguished from all stamps of the character in which the crushing-heads are loosely supported from opposite ends of a walking-beam, and one rises as the other falls. In all such stamps with which we are familiar-as, for instance, the patent to Huntington, No. 210,610, dated December 10,187S-the rising striker or stamp acts by its weight to retard the falling one, and the actual capacity for work is somewhatless than if only one stamp or striker were employed. It also differs from the common form of stamp in which the stamps act quite independently, each striking a perpendicular blow as it falls and acting by its own gravity alone. In our device the effective working force is made up from the sum of the squares of velocities of both heads or strikers and their rigidly-connected parts into their weights or nearly so. As the velocity of the movement of the stamp is a more important factor than the weight, (striking force being V W',) it is essential to effective work that the high velocity of the hammer or crusher be maintained up to the instant of impact. This we effect by letting go of the hammer before slowing down the driver preparatory to the reversal thereof.

No one familiar with steam-engineering needs to be told that the piston of a heavy high-speed engine is always cushioned or slowed down preparatory to a reversal of movement. The shock of stoppage would otherwise soon destroy any such engine. A crank movement necessarily slows down toward the dead-center. In our invention we release the stamp or striker when the engine or driver is at highest speed. The striker goes on and does its work at highest speed. The engine slows down and again takes hold of the striker for reverse movement after the blow of the striker has been given. This release of the striker or stamp from the driver clearly distinguishes our invention from such a device as that of Sharpneck, No. 279,983, patented June 20, 18:53, wherein a threearmed lever having curved lower arms provided with stamps hasits upperarm directly connected to the piston-rod of an oscillating steam-engine and is compelled to partake of the movement of the piston and rock with the exact speed of the piston movement, and our device is also distinct in its mode of operation from any stamp driven by a crank or similar movement in which the stamps are continuously connected to the crank. In other words, the momentum of both stamps at their highest velocity is available for effective work with either stamp, and such is not the factin any other machine of this character with which we are familiar.

The stamp-shoe which we prefer has its head nearly cylindrical; but its face maybe fiat, concave, or convex, according to the work, such forms being known. The two shoes and the dies are alike, and the mortars are alike at each end of the machine. Each mortar will have a feed-hopper and bin; but

for convenience we have omitted one bin in the drawings, Fig. 1. The mortar in which the die 30is inclosedis fed with lumps of rock or ore from one bin 40, which conducts the material to the vicinity of an opening 42 in the side of the mortar in which the material is crushed. The spout or hopper 41 is hinged or otherwise connected to the ore-bin 40, so as to permit a vertical movement. A rod 43 is connected to the spent and to lever 44, which lever is pivoted to a suitable support, and has one end or a projection in the line of movement of a lug 45 on the stamp-bar 20. Lug 45 may be moved and adjusted by setscrew 46, said set-screw entering holes in the segment 20, as shown in Fig. 2. When the head or shoe 21 is nearly in position to strike the die 30, the lug 45 strikes lever 44, which lever may be somewhat elastic, and thus a jerk or impulse is transmitted to the lever 44 and the rod 43 and spout 41 to shake lumps of ore or rock down into the mortar. A nut 42 on rod 43 makes adjustable connection with the spout, so that the shaking or jerking movement of the spout may be proportioned to the character of the lumps of rock or ore to be fed to the mortar. A guard or splashboard 47 guides the lumps of ore to the mortar and prevents escape'of particles from the mortar. The fall of the stamp is thus made to control the feed of the mortar in which the stamp works, and the machine does not, as is frequently the case, depend for its feed on the condition of one stamp or battery of stamps while the other .stamps may be overcrowded or running dry.

The die 30 is preferably a short cylinder with a flange at bottom, and this flange fits into the bottom of mortar 50, which mortar is preferably of cast metal,having sand-trough 51 around its upper surface and a side opening or inclined feed-chute 52, into which the ore is fed. The flared inner surface of the mortar has a nearly-annular cylindrical projection 53, to the inside of which the broken cylindrical screen 54 is secured. This screen is connected to the broken ring 55 on the top ring or band 56, and the edges of the screen are held by braces 57, extending between said ring and top band. The break in the screen thus affords a space for the entrance-spout. Outside the screen and extending above the same is the generally-cylindrical casing 60, having an opening at one side for the feed-chute 52 and an opening near the top for the entrance of the stamp. The casing 60, of sheet metal by preference, is strengthened by the internal hoops 61 and 62. The casing is cut away for the passage of the feed-chute and is partly supported by the feed-spout and partly by legs 63, which rest in sockets 66 at the top of the mortar-body. The casing is thus held above the top of the mortar to permit escape of pulverized material through the screen.

The casing '60 may have a cover 09, hinged the operation of our machine will be gener-.

ally understood. The stamp strikes quick blows at the opposite sides of its central support, each blow being an effective blow and not retarded by the slowing down of a piston or crank. Each mortar is preferably independent and complete and the operating-face of the stamp-die, shoe, and mortar-body are circular, so that there are no corners into which unbroken lumps of ore may escape. The feed can be accurately adjusted, and the delivery of the pulverized material through the screen is well provided for.

What we claim is- 1. In a stamp-mill, a rigid reciprocating stamp supported on a journaled shaft and provided with shoes at each end, a mortar and die on which the stamp may strike a blow at each end of the reciprocating movement, and means for starting the stamp-bar, then releasing the stamp-bar and permitting the momentum of both stamps and bar to become available in the blow at either end of the bar, all combined substantially as described.

2. In a stamp-mill, a stamp having a rigid curved bar with a shoe at each end to strike into a mortaras described, a journaled rockshaft having arms supporting said stamp, and a driving-motor connected to the stamp to communicate the initial rocking impulse in either direction, and then release the stamp to permit a forward movement independently of the motor, all in combination substantially as described.

3. In a stamp-mill the combination of a reciprocating piston and a bar connected thereto, a rock-shaft and an arm rigid therewith connected to said piston-bar by a connection permitting a lost motion between the motor and shaft, and a rigid curved stamp-barsupported from said shaft having shoes at each end to engage with dies, all combined.

4. In a stamp-mill, the cylinder, piston, and a bar connected to said piston, an elongated loop connected to said bar, a rock-shaft with a rigid arm in said loop, a .rigid stamp-bar supported on arms projecting from the shaft so as to be reciprocated lengthwise with the rocking of the shaft, and a mortar and die at each end of the stamp-bar, all combined substantially as described.

5. In astamp-mill, the combination with the rock-shaft supported in suitable bearings, of the rigid segmental stamp-bar rigidly connected to said shaft, a stamp-shoe at each end of the stamp-bar and a mortar and die under each stamp-shoe, a rigid arm on the rock-shaft, and a reciprocating driving-bar having an elongated loop with its ends in position to push against said bar, and to permit a movement of the arm in advance of the In testimony whereof we afiix our signa- 5 tures in presence of Witnesses.

ALEXANDER O. PRAT". CHARLES A. LA GRAVE.

Vitnesses as to signature of Alexander 0. Pratt:

Y. M. AVERELL, M. D. NOTEVVARE. \Vitnesses as to signature of Charles A. La Grave:

SAM. COHN, C. L. DEADY. 

